Double sheet detector



1551 N. H. GOLDSWORTHY DOUBLE SHEET DETECTOR 2 SHEETS-SHEET 1 Filed Dec. 21, 1945 v Wm mwa nwv wh FNIIII wrm Patented Dec. 25,1951

DOUBLE SHEET DETECTOR Norman H. Goldsworthy,

signor to Continental Can Company, Inc., New

York, N. Y.,

New York, N. Y., as-

a corporation of New York Application December 21, 1945, Serial No. 636,443

1 The invention relates generally to means for feeding metal sheets and primarily seeks to providenovel means for detecting the undesirable feeding of double sheets, or in other words sheets being fed in superposed relation.

An object of the invention is to provide, in combination with means for feeding metal sheets, electrical circuit controlling means, and means operable each time superposed or double sheets are fed to actuate said controlling means in a manner for breaking said electrical circuit.

In its more detailed nature the invention resides in providing, in combination with means for feeding metal sheets, magnet means disposed close to one face of the sheets being fed, and a circuit controlling switch means disposed at the opposite face of said sheets and including spaced contact members, a contact maker adapted to connect the contact members to complete a control circuit there across but normally movable away from the contact connecting position and having attached thereto an armature member disposed to be attracted by the magnet means and hold the contact maker in effective position when no sheets are being fed or the normal indlvldual sheets are being fed between the magnet means and said armature member, the passage of superposed sheets serving to reduce the magnetic attraction normally efl'ective to maintain the contact maker in the circuit completing position and permit the contact maker to move away and break the control circuit.

With the above and other objects in view that will hereinafter appear, the nature of the invention willbe more clearly understood by reference to the following detailed description, the appended claims, and the several views illustrated in the accompanying drawings.

In'the drawings:

Figure 1 is a somewhat diagrammatic side elevation illustrating one adaptation of the invention.

Figure 2 is an enlarged vertical longitudinal section'illustrating the control switch and magnet means in cooperative relation.

Figure 3 is a detail planview of the switch tube removed from the casing shown in Figure 2.

- Figure 4 is a view similar to Figure 2 illustrating an alternative form of control switch.

- 'In the ekample of the invention herein dis- I closed, there are included conveyor means 5 having' feed dogs 6 for-feeding metal sheets lalong suitable feedways 8. The metal sheets may be placed on the conveyor by hand, or by any approved mechanical means from a. stack 8 or any 6 Claims. (01. 192127) other suitable supply source, and said sheets maybe fed by the conveyor means to any work station, such as the punching station It diagrammatically illustrated in Figure 1 whereat end closures or comparable blanks are to be formed. The conveyor means may be driven by any suitable drive couple II from a motor it.

Magnet means l3 which may take the form of a permanent magnet or an electro-magnet is disposed close beneath the path. of travel of the sheets i in the manner clearly illustrated in Figures 1 and 2. it will be apparent that the magnet means is so disposed that the sheen t are fed thereover without contacting the same. A circuit control switch unit generally designated I4 is disposed directly over the magnet means, and it too is so placed that the sheets may be fed thereunder without contacting the same.

The control switch unit illustrated in Figure 2 includes a brass casing or housing having a removable cover IS. A bracket i1 is verticallyadjustably secured as at [8 to one wall of the casing and includes a horizontal shelf portion is. A supporting bar formed of insulating material is laterally-adjustably secured as at 2| to depend beneath the shelf l9 and extend longitudinally in the casing I5. Two contact terminals 22 and 23 are mounted at the respective ends of the bar 20, and it will be apparent by reference to Figure 1 that the contact terminals are connected as at 24 with the motor I! and as at 25 with a power line 26. The motor also is connected as at 21 with the power line 28, and it will be apparent that when the control switch contacts 22 and 23 are electrically connected in a manner soon to be described, the motor II will be operated and movement will be imparted to the conveyor means 5 for feeding metal sheets. It will also be apparent that when the electrical connection between the control switch contacts 22 and 23 is broken, the supply of power to the motor will be discontinued and movement of the conveyor 5 will stop.

Spring contact clips 29 and 30 are connected with and depend from the contact members 22 and 23 respectively, and said clips yieldably embrace and retain the contact caps 3| and 32 attached to the respective ends of the switch tube 33 which is removably mounted within the switch casing IS. The detail structure of the switch tube will be apparent by reference to Figures 2 and 3 of the drawings.

It will be observed that the switch tube is shaped at one end to provide a, well 34 in which is retained a blob of mercury 35, the latter being e..ctrically connected as at it with the adjacent end cap 32. At the other end of the tube, a pivot bracket 31 is electrically connected as at 84 with the other end cap M. A stirrup 39 is pivotally connected to the bracket, and at its free end the stirrup is attached to a soft steel armature bar 40 having a contact member 3| projecting from the free end thereof and including a depending portion 42 normally engageable in the mercury blob-35. A spring 48 is secured to the armature 40 and coiled about and secured to the bracket 31 in a manner for constantly tending to lift the armature bar from the normal position illustrated in Figure 2 to displace the contact end portion 42 and disrupt the normal electrical connection between the contact caps 3i and 3t and the contact members 22 and 23 engaged thereby. During the normal feeding of the metal sheets, the parts are positioned in the manner illustrated in Figures 1 and 2, and the metal sheets I will be fed between the magnet means it and the overlying control switch unit M with their upper and lower faces closely approximating but not contacting with the upper and lower faces of said magnet means and control unit. In this normal condition of the parts, the magnet means attracts the soft steel armature bar 40 to maintain the electrical connection through the switch tube and the resulting driving connec-- tion between the motor and its supply source, and this condition pertains during the normal feeding of individual sheets and also at such times when the conveyor may be driven without any sheets I thereon.

Should any double or superposed sheets be deposited on the conveyor 5 and moved thereby between the magnet means l3 and the overlying control unit l4, the presence of the added metal sheet thickness will so weaken the effective ma netic field above the superposed sheet thickness as to discontinue the attraction of the soft steel armature bar 40 and permit the spring 43 to lift said bar and displace the contact end portion 42 for the mercury blob 35, thereby breaking the control circuit and discontinuing the operation of the motor l2 and the movement of the conveyor 5.

While a simple motor stopping control circuit is shown herein as an example of embodiment of the invention, it is to be understood that the control devices may be operatively connected in more complicated electrical control circuits and employed in connection with sheet ejecting means, if desired. It will also be obvious that instead of the form of permanent magnet means illustrated in Figure 2, ordinary horse-shoe magnet means or electro-magnet means may be used.

In Figure 4 of the drawings there is illustrated an alternative form of control switch means in which there is included a casing 44 having a bearing 45 in which is slidably mounted an uprightly disposed plunger 46. The plunger carries a soft steel armature 41 at its lower end in position for being slightly spaced above the travelling sheets and directly over magnetic means generally designated 48 disposed in slightly spaced relation below said travelling sheets.

Within the casing 44, the plunger 46 is equipped with abutment means 49, and a coil spring 50 is interposed between the abutment means and the bearing 45 and constantly tends to lift the plunger. At its upper end the plunger carries a contact bar 5| having contacts 52 and 53 at its respective ends engageable with the fixed contacts 54 and 55 carried by the casing.

The fixed contacts 54 and 55 maybe. acted withthe motor and the power source in the man ner diagrammatically illustrated in Figure l, and it will be apparent that during normal feed: ing of individual sheets 65 the armature dl will be attracted by the magnet means $8 in a manner for normally holding the contacts 52, 8t and 53, 55 in the circuit completing or contacting condition. As in the case of the previously de= scribed control switch unit, when double or superposed metal sheets are fed between the magnet means 48 and the armature til, the magnet means will no longer be able to overcome the action of the spring 58 and said spring will force the plunger upwardly and break the motor driv= ing circuit by separation of the contacts 52, 5t and 53, 55.

While one form of the invention has been shown for purposes of illustration, it is to be clearly understood that various changes in the details of construction and arrangement of parts may be made without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. In apparatus of the character described, in combination; means for feeding metal sheets of predetermined normal thickness; magnet means disposed close to one face of the sheets being fed; and a circuit controlling switch means disposed at the opposite face of said sheets and including spaced contact members, a contact maker adapted to connect the contact members to complete a control circuit thereacross, means biasing said contact maker so that it is constantly tending to move away from its contact connecting position, said contact maker including an armature member disposed to be attracted by the magnet means, said magnet means and said biasing means being so cooperatively valued as to magnetic attraction and biasing efiect respectively as to be effective to hold the contact maker in the contact connecting position only when no sheets are being fed or when individual sheets of said predetermined normal thickness are being fed between the magnet means and said armature member, whereby passage of superposed sheets of said predetermined normal thickness between said magnet means and said armature member will reduce the effective magnetic attraction normally active to hold the contact maker in the contact connecting position and permit the contact maker to move away from its contact making position and break the control circuit. v

2. In apparatus of the character described, in combination; means for feeding metal sheets of predetermined normal thickness including a driving motor and a supply circuit; magnet means disposed close to one face of the sheets being fed; and a circuit controlling switch means disposed at the opposite face of said sheets and including spaced contact members connected in said supply circuit, a contact maker adapted to connect the contact members to complete said supply circuit, means biasing said contact maker so that it is constantly tending to move away from its contact connecting position, said contact maker including an armature member disposed to be attracted by the magnet means, said magnet means and said biasing means being so cooperatively valued as to magnetic attraction and biasing efiect respectively as to be elites- .tive to hold the contact maker in the contact connecting position only when no sheets are being feed or when individual sheets of said predetermined normal thickness are being fed between the magnet means and said armature member, whereby passage of superposed sheets 01' said predetermined normal thickness between said magnet means and said armature member will reduce the eiiective magnetic attraction normally active to hold the contact maker in the contact connecting position and permit the contact maker to move away from its contact making position and break the supply circuit.

3. In apparatus of the character described, in combination, means for feeding metal sheets of predetermined normal thickness individually past a testing station, control switch means disposed in close proximity to one face of sheets being fed past said station and connected in a control circuit and including a circuit completing contact maker magnetically attractable to a circuit complating position, means biasing said contact maker so that it is constantly tending to move away from said position to break the circuit, and magnet means disposed opposite said switch means and in close proximity to the opposite race of sheets being fed past said station, said magnet means and said biasing means being so cooperatively valued as to magnetic attraction and biasing eilect respectively as to be eifective when no sheets are being fed or when individual sheets of said predetermined normal thickness are being fed past said station to hold the contact maker in its circuit closing position but ineflective to so hold the contact maker when superposed sheets oi' said predetermined normal thickness are fed past said station, thereby to permit the contact maker to move to the circuit breaking position whenever such superposed sheets are presented between said magnet means and said switch means.

4. In apparatus of the character described, in combination, means for feeding metal sheets of predetermined normal thickness individually pasta testing station, driving means for said feeding means including an electric motor, control switch means disposed in close proximity to one face of sheets being fed past said station and connected in a supply circuit and including a circuit completing contact maker magnetically attractable to a circuit completing position, means biasing said contact maker so that it is constantly tending to move away from said position to break the circuit, and magnet means disposed opposite said switch means and in close proximity to the opposite face of sheets being fed past said station, said magnet means and said biasing means being so cooperatively valued as to magnetic attraction and biasing eflect respectively as to be eilective when no sheets are being fed or when individual sheets of said predetermined normal thickness are being fed past said station to hold the contact maker in its circuit closing position but ineflective to so hold the contact maker when superposed sheets of said predetermined normal thickness are fed past said station, thereby to permit the contact maker to move to the circuit 8 breaking position whenever such superposed sheets are presented between said magnet means and said switch means.

5. In apparatus of the character described, in combination, means for feeding metal sheets of predetermined normal thickness individually past a testing station, control switch means disposed in close proximity to one face of sheets being fed past said station and connected in a control circuit and includin a circuit completing contact maker magnetically attractable to a circuit completing position, spring means constantly tending to move the contact maker away from its circuit completing position, and magnet means disposed opposite said switch means in position for projecting a magnetic field across the path of travel of the sheets of such strength relative to said spring means as to be effective when no sheets are being fed or when individual sheets of said predetermined normal thickness are being fed past said station to attract and hold the contact maker in its circuit closing position but ineffective to so hold the contact maker whenever superposed sheets of said predetermined normal thickness are fed past said station, thereby to permit the spring means to move the contact maker to a circuit breaking position.

6. In apparatus of the character described, in combination, means for feeding metal sheets of a predetermined normal thickness individually past a testing station, driving means for said feeding means including an electric motor, control switch means disposed in close proximity to one face of sheets being fed past said station and connected in a supply circuit and including 'a circuit completing contact maker magnetically attractable to a circuit completing position, spring means constantly tending to move the contact maker means disposed opposite said switch means in position for projecting a magnetic field across the path of travel of the sheets of such strength relative to said spring means as to be effective when no sheets are being fed or when individual sheets of said predetermined normal thickness are being fed past said station to attract and hold the contact maker in its circuit closing position but ineffective to so hold the contact maker whenever superposed sheets of said predetermined normal thickness are fed past said station, thereby to permit the spring means to move the contact maker to a circuit breaking position.

NORMAN H. GOLDSWOR'I'HY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,218,988 Droitcour Mar. 13, 1917 2,189,597 Wells Feb. 6, 1940 2,235,104 Greenly Mar. 18, 1941 2,245,596 Lindberg June 1'7, 1941 2,323,351 Pechy July 6, 1943 

